1 . Field of the Invention
The present invention relates to resin windows having conductive elements that may preferably be used instead of glass windows for a vehicle, and more particularly, to terminal mounting structures for a resin window having a conductor, such as an antenna or a defogger.
2. Description of the Related Art
Glass windows having antennas for receiving radio broadcasts and defoggers for preventing window fogging are known. These windows utilize a metal conducting wire disposed within the glass to conduct electric signals or heat to provide useful functions.
An example of a known antenna terminal structure provided on a window 31 is shown in FIG. 12 and a perspective view of part B is shown in FIG. 13. The antenna 32 is formed in the glass window by printing an electrically conductive ink in a predetermined pattern on the interior side of the window shield glass 31 and then baking the ink and glass to harden the ink. A relatively wide conducting portion 33 is formed to contact the antenna 32 in order to provide a sufficient electrical connection between the antenna 32 and a terminal 34, which is mounted on the conducting portion 33 using solder 35. A method for manufacturing a glass window with such a conductor is disclosed in Japanese Laid-Open Patent Publication No. 63-155804.
Recently, resin windows have begun to replace glass windows in automobile in order to reduce the overall weight of the vehicle. However, in order to dispose a conductor in the resin window, several problems are presented due to the generally low heat resistance of the resin panel. For example, if an antenna is printed on the resin panel, the baking temperature must be lower than can be withstood by a glass window. Therefore, such antennas may have low resistance to wear and may be susceptible to breakage by contact with other objects. Similarly, low-melting solders, which can be used within the allowable range of temperatures that the resin panel can endure, generally have inferior bonding strength. Therefore, the techniques for making a glass window structures cannot be directly applied to resin windows.
As one technique, a conductor print could be formed on a resin film by printing electrically conductive ink on one side thereof and then such resin film could be joined to a resin panel with the conductor print side on the inside surface. In this way, the conductor print would be interposed between the resin panel and the resin film. In this case, a conducting portion made of a conductive material (such as metal) is to be provided at a portion of the conductor print for connecting the conductor print to a terminal that is secured to the resin panel. However, if an opening is formed in the resin to expose the conducting portion through the opening on the window surface, the resin film may be easily separated at the edge of the opening.
Specifically, as compared with the resin-to-resin adhesion between the resin panel and the resin film, the adhesion of non-resin to resin around the conducting portion that is typically made of metal conductive material is relatively weak. In addition, the opening that defines a recessed portion is subject to external forces, during manufacturing operation or when cleaning the window surface. As a result, the resin film may be separated at the edge of the opening, and thus, the conductor print may also be separated together, which will affect the conductivity to the conducting portion.
Also, useful techniques have not yet been developed for mounting an electrically conductive terminal structure on a resin window having a conductor disposed within the resin window. For example, a conductor could be formed in a resin window using known techniques by printing electrically conductive ink on one side of the resin window and soldering the terminal structure to the conductor. However, solders that have been used for glass windows generally have high melting temperatures. Therefore, such solders can not be used to secure a terminal to a resin panel, because resin panels typically have low resistance to heat. As a result, the resin panel will warp or melt by the application of heat to the resin panel.
In the alternative, electrically conductive adhesives or low-melting solder could be used. However, these adhesives and solder usually have inferior bonding strengths and reliability compared to the known high-melting point solders.
Therefore, a need exists in the art to provide a resin window having a conducting portion disposed in or on the resin window and having a terminal structure reliably connected to the conducting portion.